/**
 * @param {number} n - a positive integer
 * @return {number} - a positive integer
 */
 var reverseBits = function(n) {
   let num = 0, t = 32;
   while(t--) {
     num = num << 1;
     num |= (n & 1);

     n = n >>> 1;
   }
};
let a = 0b1001;
console.log(a);
